1. Field of the Invention
The present invention relates to the acidulation of meat and other food products and particularly to a method of acidulating, and a coated acidulant, effective in low temperature food processing.
2. Description of the Prior Art
The acidulation of meat products, particularly meat emulsions, is well known. Meat emulsions, for instance sausage emulsions, are mixtures of lean meat or meat protein and water forming a matrix in which fat particles, salt, sugar and curing agents are dispersed. It is also well known that meat emulsions will set up and harden as the pH of the emulsion decreases. Therefore, in order to assure easy processability, it is necessary to avoid lowering the pH of the emulsion during the early stages of preparation and processing. For instance, meat emulsions begin to harden at pHs below about 5.2 and especially at pHs below about 5.0, making it impossible to stuff the meat into casings for the production of sausages and like products. Generally, the emulsions remain processable at pHs above about 5.2. However, it is desirable to lower the pH of the final product below this level in order to enhance flavor and appearance (i.e. color), achieve a more solid texture and lengthen storage life.
Acidulation of food in the past has been accomplished by various means. One method comprises inoculating the food mass with a small amount of previously fermented food. The resulting inoculated food mass was then allowed to ferment for an extended period of time. Fermentation using this method was very slow due to the time required for bacteria to grow and produce acids (usually lactic acid) which eventually lowered the food pH to the desired level.
Another method of acidulating food comprises adding acid directly to the food. In meat emulsions and like products, especially ground meat products, localized high concentrations of acid (so-called "hot spots") must be avoided since they can degrade the appearance and taste of the finished food product. In order to avoid this problem, the acid must be quickly dispersed throughout the food mass. This requires special mixing apparatus able to operate under extremely stringent parameters. Even in cases where the added acid could be quickly and effectively dispersed, there remained the problem of substantially instantaneous set-up (hardening) of the food, before the final food processing steps could be completed.
One solution to the fast set-up problem was to add glucono delta lactone, rather than an acid, directly to the food. Glucono delta lactone reacts with water present in the food and hydrolyzes into gluconic acid. In practice, it was discovered that the acid-producing glucono delta lactone had a tendency to prematurely hydrolyze, and accordingly, had to be quickly dispersed throughout the emulsion. Due to the difficulty in controlling the rate and extent of hydrolysis, glucono delta lactone has only received limited acceptance as a food acidulant.
Another approach has been to coat solid granular acids with either a wax, a monoglyceride or a vegetable oil. When meats containing these coated granular acids are subjected to higher temperatures, such as in a smokehouse, the coatings melt thereby releasing the acid. For example, U.S. Pat. Nos. 4,537,784 and 4,511,584 both disclose lipid coatings for micro-encapsulated solid granular acids useful in food processing at temperatures in the range of 100.degree.-150.degree. F. The coatings are primarily triglycerides, but may also contain mono- and diglycerides. These patents further disclose that when the temperature of the food containing the coated acidulant is raised above the melting point of the triglyceride coating, the coating melts thereby releasing the acid. One problem with this procedure is that not all foods are processed at temperatures above 100.degree. F. For instance, summer sausage, Genoa salami, and some German sausages are subject to maximum (i.e, smokehouse) temperatures of only 75.degree.-80.degree. F., which is below the melting point temperature of these types of acidulant coatings. Although acidulant coatings having a melting point in the range of about 75.degree. -80.degree. F. are known, acidulants having these coatings must be refrigerated until immediately before use, otherwise there is the danger of premature melting during shipment and handling.
U.S. Pat. No. 4,511,592 discloses an acidulant coating which does not depend upon melting the coating in order to release the acidulant. The coating material disclosed in this patent comprises an edible hydrolized starch and a protein. Once this coating comes in contact with water contained in the meat emulsion, the coating quickly dissolves thereby releasing the acid. In practice, it was discovered that the coatings disclosed in U.S. Pat. No. 4,511,592 are so water soluble that very little acid release delay is provided. For instance, in cases where the coating is extremely thick, (i.e., in cases where the coating comprises about 50 wt. % of the coated acidulant) the coating typically dissolves and releases the acid in a matter of minutes. In industrial processes, this is insufficient time in order to complete the processing of the meat emulsion, i.e. to stuff it into casings in the case of sausage production.
Thus, there has been a need in the art for an acidulant and a method of acidulating meat emulsions and other food materials which are subject to lower processing and smoking temperatures and yet which still provides adequate time delays, on the order of at least one and preferable at least two hours, before enough of the acidulant is released to lower the pH to a level where the food material sets up.